Optical devices such as telescopes, binoculars, microscopes and night vision goggles, each require one or more optical lenses, and often include other accessory attachments. The accessories are typically placed in the optical path with the lens, and may include, for example, protective glass plates or masks, filters and etc. in a holder. Such lenses and accessories are maintained in the optical path by the holder which is snapped or threaded onto the optical device.
Various methods for securing the lens within the lens holder have been previously used. One method typically employed is to form a flange in the lens holder against which the lens is positioned. A ring is then installed against the lens and is secured with an adhesive to the lens and the lens holder. This method is time consuming and subject to error and is therefore expensive. Also, it is difficult to apply the adhesive in an efficient manner to secure the ring and the lens in position without smearing some of the adhesive over the lens, thereby ruining the lens or requiring disassembly of the eyepiece and cleaning.
Another commonly used method is to replace the glued ring with a split snap ring. This method requires the formation of an internal annular groove in the lens holder into which the snap ring fits to maintain the lens in place. The snap ring generally comprises metal, the insertion of which may require pliers and therefore can be difficult and time consuming. Often the lens is scratched or damaged, especially if constructed of plastic, when the ring is compressed and inserted into the annular groove. Also, if the lens is coated with a protective covering such as, for example, a delicate hygroscopic coating (an anti-mist or de-fogging coating), such coating may be damaged or partialy removed by insertion of the ring. Thus, a need has arisen for an optical element retainer which is inexpensive and which can be employed to quickly and easily clamp lenses into a lens holder without damage to the optical elements.